Implanting a chronic electrical stimulator, such as a cardiac stimulator or a neural stimulator, to deliver medical therapy(ies) is known. Examples of cardiac stimulators include implantable cardiac rhythm management (CRM) devices such as pacemakers, implantable cardiac defibrillators (ICDs), and implantable devices capable of performing pacing and defibrillating functions. Examples of neural stimulators include neural transducers, peripheral nerve stimulators, e.g., vagus nerve stimulators, and cortical stimulators.
One technique for providing artificial neural stimulation entails implanting an electrode into direct contact with a portion of a selected nerve to influence a baroreflex. A separate, battery-powered activation source or triggering device is likewise implanted and connected to the electrode. The electrode is periodically activated by the triggering device, thereby stimulating the nerve in question and prompting a baroreflex decrease in heart rate. Essentially, activation of the electrode serves to simulate a rise in blood pressure, causing the baroreflex reduction in heart rate.
CRM devices are implantable devices that provide electrical stimulation to selected chambers of the heart in order to treat disorders of cardiac rhythm. An implantable pacemaker, for example, is a CRM device that paces the heart with timed pacing pulses. If functioning properly, the pacemaker makes up for the heart's inability to pace itself at an appropriate rhythm in order to meet metabolic demand by enforcing a minimum heart rate. Some CRM devices synchronize pacing pulses delivered to different areas of the heart in order to coordinate the contractions. Coordinated contractions allow the heart to pump efficiently while providing sufficient cardiac output.
Heart failure refers to a clinical syndrome in which cardiac function causes a below normal cardiac output that can fall below a level adequate to meet the metabolic demand of peripheral tissues. Heart failure may present itself as congestive heart failure (CHF) due to the accompanying venous and pulmonary congestion. Heart failure can be due to a variety of etiologies such as ischemic heart disease.
Following a myocardial infarction, myocytes in the infarcted region die and are replaced by scar tissue, which has different mechanical and elastic properties from functional myocardium. Over time, this infarcted area can thin and expand, causing a redistribution of myocardial stresses over the entire heart. Ventricular remodeling following a myocardial infarction frequently leads to impaired mechanical function and heart failure.
What is needed is an improved method for cardiac repair.